I haven't read the story in years and have no recollection of battle details.
Did you determine any range limitations for the heat ray? It probably would have a focal length where it reaches optimum power. Beyond that armored ships and vehicles would stand a better chance of surviving.
Is there any indication of rate-of-fire for the heat ray? It is a high powered weapon but may have cyclic restrictions. That would allow the tripod to be swarmed by missiles and/or gunfire.
Did any of the tripods take damage from an actual human weapon other than ramming?
Modern tanks can penetrate the equivalent of over 40" of armor steel and at a pretty good range. They are also very accurate. The tripod legs or cluster joint at the hull might be vulnerable.
If we were desperate enough we could also employ chemical/biological weapons. In the book the Martians die from exposure to our diseases so they must not be running a sealed air system inside their tripods.
Thanks for your work on the calculations for the heat ray.